The services defined in ISO/IEC 22534:2005 are used to establish and maintain a relationship between an application and a server for the purpose of exchanging application messages. For the purpose of ISO/IEC 22534:2005, this relationship is called an application session.

Application protocols, such as ECMA-323, require that an application session is established before application messages are exchanged. ECMA-269 specifies several mechanisms for establishing an application context. One possible mechanism is ACSE (ISO/IEC 8649) - but since ASCE uses ASN.1 encoding for its services, it is not desirable for use with XML based protocols such as ECMA-323.